4 Watson, On tJic U lode nd raid Scar. 



pyrites and probabl}' iron carbonate, which must represent 

 some portion of the original plant, and which is not a 

 cast. 



In the reverse (see Fi[(^. 2, Plate /.), the continuation of 

 this ring is seen, and it is seen to give origin to numerous 

 small strands which pass outwards. In one place on the 

 lower half of the scar these are intercepted by a plane of 

 fracture, and have the arrangement of dots characteristic 

 of ordinary Ulodendroid scars in this region. 



These strands and the tissue in which they run are 

 imperfectly petrified. 



I think that the appearances seen on this specimen 

 cannot be explained on the orthodox view, but receive a 

 ready explanation by the theory that the scar represents 

 the base of a branch attached to the whole scar. 



The explanation I wish to propose is as follows : — 



That a small portion of the base of this branch still 

 remains attached to the scar, and that this patch of tissue 

 was much macerated and decayed before fossilization, all 

 its soft tissues being removed, whilst its vascular system 

 was left almost intact.* 



I believe that this fragment of the base 01 the branch 

 was then imperfectly petrified. 



The ring surrounding the depression in the umbilicus 

 is, I believe, the actual primary wood cylinder, and the 

 small strands to which it gives origin are leaf traces 

 which pass outwards to supply leaves attached to the 

 branch. 



The size of the Ulodendroid scar is 95 mm. by 80 mm. 

 On the branch theory 80 mm., the horizontal diameter, 

 will represent the diameter of the base of the branch. On 

 the assumption that the upstanding ring round the 



*We know from the evidence of petrified stems that this is how Lepido- 

 dendroid branches did decay. 



